1. Field of the Invention
One or more embodiments of the present invention relate to color rendering, and more particularly, to an illuminant estimation method, medium, and system estimating an illuminant for white balancing.
2. Description of the Related Art
Color temperature is a term used to describe the color of light and is typically measured in degrees Kelvin (K). In general, human visual perception is characterized by autonomously adjusting color sensitivity. Thus, the human visual system may not be able to properly detect changes in the color temperature of light. On the other hand, image pickup devices such as cameras or camcorders can precisely sense the color temperatures of illuminants. Thus, images captured under different illuminants by an image pickup device may actually render the same object in different colors.
For example, the color temperature of sunlight on a clear day is high, such that corresponding images captured by an image pickup device will generally appear bluish. On the other hand, the color temperature of sunlight before sunrise or after sunset is low, and corresponding images captured by an image pickup device will generally appear reddish. In order to address this problem, automatic white balancing (AWB) has been suggested. AWB is a technique of correcting color distortions in an image when at least one of R, G, and B components of the image prevails because of the color temperature of an illuminant.
However, conventional white balancing techniques may not be able to perform consistent color rendering on images according to the colors and sizes of objects rendered therein even though the images are captured under the same illuminant.
In addition, the illuminant estimation performance of conventional white balancing techniques may considerably deteriorate, especially when images include no illuminant information or when images only include object colors that are similar to an illuminant.